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Corrosion of carbon steel casing foreseen in the high level radioactive waste facility monitored by acoustic and electrochemical techniques

Nicolas Bulidon
  • Fonction : Auteur
J. Bolivar
  • Fonction : Auteur
S. Necib
  • Fonction : Auteur
O. Fedrigo
  • Fonction : Auteur
G. Girardin
  • Fonction : Auteur

Résumé

The French national radioactive waste management agency (Andra) is designing an industrial centre for geological disposal (CIGEO1) of Intermediate Level Long-Lived radioactive waste (ILL-LW) and High Level Waste (HLW). The facility is based on a multi-barrier waste confinement concept which must be reversible and monitored for at least 100 years. First, vitrified waste are introduced in a stainless steel container and set into an overpack made of low alloyed steel. Then, the overpacks are introduced into micro-tunnels drilled in the claystone and cased with a micro-alloyed steel pipe (API 5L X65 grade). The pipe is in direct contact with a cementitious bentonite grout material. This material is expected to neutralize the potential acidity resulting from the excavation of the micro-tunnel and the progressive resaturation of claystone. The present work takes part of the SCCoDRa project (French acronym for “Monitoring of metallic components corrosion for radioactive waste disposal). This four-year industrial project is partly devoted to the improvement of corrosion monitoring methods applied to corrosion processes foreseen in the High Level Waste facility. Many parameters of the environment will evolve during the operating phase: aerated conditions followed by a progressive consumption of oxygen by various processes, temperature, pH, water resaturation of the host rock…, are expected. So during this period, different corrosion modes may occur like uniform corrosion, crevice corrosion and smaller corrosion attacks. The present work focuses on the capacity of Acoustic Emission (AE) and Electrochemical Noise (EN) techniques to detect and to distinguish these two corrosion modes. Acoustic Emission is known to be a sensitive technique to corrosion elementary processes such as hydrogen evolution, thick corrosion products breakdown, plastic deformation, cracking… [1] Yet, the technique presents some limitations: dissolution processes are not energetic enough to be detected by piezoelectric sensors, and only evolution of corrosion processes can be detected; no information can be obtained about the geometry of the damage by AE. Moreover, AE is sensitive towards elementary mechanisms that can be common to several corrosion modes (e.g. gas evolution), thus it cannot allow identifying the corrosion modes that occurs. Finally, it is strongly dependant on the acquisition chain: sensor, amplification, acquisition parameters. On the other hand, EN features observation (both temporal and frequential) can allow identifying corrosion mode, its kinetics and transitions from one to another [2]. In this context, the aim of the present work is to evaluate potentialities of both techniques, individually and coupled, to detect, identify and quantify corrosion damage of carbon steel in the context of nuclear waste storage. Experimental devices and procedures are developed to control corrosion processes, in terms of geometry and rate, while being representative of actual damage conditions. The variation of parameters related to the medium (temperature, pH, nature of the species) allows this control. The variations in the parameters of the resulting EA and EN signals are analyzed and correlated with observations of damage evolution. References [1] S.Yuyama, “Fundamental Aspects of Acoustic Emission Applications to the Problems Caused by Corrosion”, presented at the Corrosion Monitoring in Industrial Plants Using Nondestructive Testing and Electrochemicals methods, Phiadelphia, 1986, vol. ASTM STP 908, pp. 43-74. [2] A.M Homborg, T. Tinga, E.P.M van Westing, X. Zhang, G.M Ferrari, J.H.W de Wit, J.M.C. Mol, “A Critical Appraisal of the Interpretation of Electrochemical Noise for Corrosion Studies”, Corrosion The Journal of Science and Engineering, 2014, vol. 70, No. 10, pp. 971-987.

Domaines

Chimie
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Dates et versions

hal-03967171 , version 1 (02-03-2023)

Identifiants

  • HAL Id : hal-03967171 , version 1

Citer

Chloé Comas, Marion Fregonese, Nicolas Bulidon, J. Bolivar, S. Necib, et al.. Corrosion of carbon steel casing foreseen in the high level radioactive waste facility monitored by acoustic and electrochemical techniques. 7th International Workshop LTC 2019, CEFRACOR, Nov 2019, Nancy, France. ⟨hal-03967171⟩
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